Groundwater in high mountains: Climate change impacts on a hidden water resource

Abstract:

Mountain water resources are of particular importance for downstream populations but are threatened by decreasing water storage in snowpack and glaciers. Groundwater contribution to mountain streamflow, once assumed to be relatively small, is now understood to represent an important water source to mountain streams and rivers. Drawing on global examples and highlighting our work in the Peruvian Andes, I will summarize how groundwater is stored and transmitted through high mountain watersheds and how mountain groundwater dynamics are expected to change in a warming climate. High mountains represent a complex and heterogeneous groundwater flow system where groundwater is channeled through both coarse surficial geomorphic units and shallow and deep bedrock. Recent advances suggest that high mountain groundwater may provide some resilience – at least temporarily – to water resources under climate driven glacier and snowpack recession. However, mountain groundwater is vulnerable to decreasing recharge due to changing snowpack, changing vegetation and increasing evapotranspiration. A decrease in mountain groundwater recharge will decrease river baseflows and have important implications for downstream water users.